1,006 research outputs found
Covid-19 classification with deep neural network and belief functions
Computed tomography (CT) image provides useful information for radiologists
to diagnose Covid-19. However, visual analysis of CT scans is time-consuming.
Thus, it is necessary to develop algorithms for automatic Covid-19 detection
from CT images. In this paper, we propose a belief function-based convolutional
neural network with semi-supervised training to detect Covid-19 cases. Our
method first extracts deep features, maps them into belief degree maps and
makes the final classification decision. Our results are more reliable and
explainable than those of traditional deep learning-based classification
models. Experimental results show that our approach is able to achieve a good
performance with an accuracy of 0.81, an F1 of 0.812 and an AUC of 0.875.Comment: medical image, Covid-19, belief function, BIHI conferenc
Making use of partial knowledge about hidden states in HMMs : an approach based on belief functions.
International audienceThis paper addresses the problem of parameter estimation and state prediction in Hidden Markov Models (HMMs) based on observed outputs and partial knowledge of hidden states expressed in the belief function framework. The usual HMM model is recovered when the belief functions are vacuous. Parameters are learnt using the Evidential Expectation- Maximization algorithm, a recently introduced variant of the Expectation-Maximization algorithm for maximum likelihood estimation based on uncertain data. The inference problem, i.e., finding the most probable sequence of states based on observed outputs and partial knowledge of states, is also addressed. Experimental results demonstrate that partial information about hidden states, when available, may substantially improve the estimation and prediction performances
Strategies to face imbalanced and unlabelled data in PHM applications.
International audienceAccuracy and usefulness of learned data-driven PHM models are closely related to availability and representativeness of data. Notably, two particular problems can be pointed out. First, how to improve the performances of learning algorithms in presence of underrepresented data and severe class distribution skews? This is often the case in PHM applications where faulty data can be hard (even dangerous) to gather, and can be sparsely distributed accordingly to the solicitations and failure modes. Secondly, how to cope with unlabelled data? Indeed, in many PHM problems, health states and transitions between states are not well defined, which leads to imprecision and uncertainty challenges. According to all this, the purpose of this paper is to address the problem of "learning PHM models when data are imbalanced and/or unlabelled" by proposing two types of learning schemes to face it. Imbalanced and unlabelled data are first defined and illustrated, and a taxonomy of PHM problems is proposed. The aim of this classification is to rank the difficulty of developing PHM models with respect to representativeness of data. Following that, two strategies are proposed as pieces of solution to cope with imbalanced and unlabeled data. The first one aims at going through very fast and/or evolving algorithms. This kind of training scheme enables repeating the learning phase in order to manage state discovery (as new data are available), notably when data are imbalanced. The second strategy aims at dealing with incompleteness and uncertainty of labels by taking advantage of partially-supervised training approaches. This enables taking into account some a priori knowledge and managing noise on labels. Both strategies are proposed as to improve robustness and reliability of estimates
MEDL-U: Uncertainty-aware 3D Automatic Annotation based on Evidential Deep Learning
Advancements in deep learning-based 3D object detection necessitate the
availability of large-scale datasets. However, this requirement introduces the
challenge of manual annotation, which is often both burdensome and
time-consuming. To tackle this issue, the literature has seen the emergence of
several weakly supervised frameworks for 3D object detection which can
automatically generate pseudo labels for unlabeled data. Nevertheless, these
generated pseudo labels contain noise and are not as accurate as those labeled
by humans. In this paper, we present the first approach that addresses the
inherent ambiguities present in pseudo labels by introducing an Evidential Deep
Learning (EDL) based uncertainty estimation framework. Specifically, we propose
MEDL-U, an EDL framework based on MTrans, which not only generates pseudo
labels but also quantifies the associated uncertainties. However, applying EDL
to 3D object detection presents three primary challenges: (1) relatively lower
pseudolabel quality in comparison to other autolabelers; (2) excessively high
evidential uncertainty estimates; and (3) lack of clear interpretability and
effective utilization of uncertainties for downstream tasks. We tackle these
issues through the introduction of an uncertainty-aware IoU-based loss, an
evidence-aware multi-task loss function, and the implementation of a
post-processing stage for uncertainty refinement. Our experimental results
demonstrate that probabilistic detectors trained using the outputs of MEDL-U
surpass deterministic detectors trained using outputs from previous 3D
annotators on the KITTI val set for all difficulty levels. Moreover, MEDL-U
achieves state-of-the-art results on the KITTI official test set compared to
existing 3D automatic annotators.Comment: 6 pages Main, 1 page Reference, 5 pages Appendi
Evidential deep learning for arbitrary LIDAR object classification in the context of autonomous driving
International audienceIn traditional LIDAR processing pipelines, a point-cloud is split into clusters, or objects, which are classified afterwards. This supposes that all the objects obtained by clustering belong to one of the classes that the classifier can recognize, which is hard to guarantee in practice. We thus propose an evidential end-to-end deep neural network to classify LIDAR objects. The system is capable of classifying ambiguous and incoherent objects as unknown, while only having been trained on vehicles and vulnerable road users. This is achieved thanks to an evidential reformulation of generalized logistic regression classifiers, and an online filtering strategy based on statistical assumptions. The training and testing were realized on LIDAR objects which were labelled in a semi-automatic fashion, and collected in different situations thanks to an autonomous driving and perception platform
Surveying human habit modeling and mining techniques in smart spaces
A smart space is an environment, mainly equipped with Internet-of-Things (IoT) technologies, able to provide services to humans, helping them to perform daily tasks by monitoring the space and autonomously executing actions, giving suggestions and sending alarms. Approaches suggested in the literature may differ in terms of required facilities, possible applications, amount of human intervention required, ability to support multiple users at the same time adapting to changing needs. In this paper, we propose a Systematic Literature Review (SLR) that classifies most influential approaches in the area of smart spaces according to a set of dimensions identified by answering a set of research questions. These dimensions allow to choose a specific method or approach according to available sensors, amount of labeled data, need for visual analysis, requirements in terms of enactment and decision-making on the environment. Additionally, the paper identifies a set of challenges to be addressed by future research in the field
Probabilistic Logic Programming with Beta-Distributed Random Variables
We enable aProbLog---a probabilistic logical programming approach---to reason
in presence of uncertain probabilities represented as Beta-distributed random
variables. We achieve the same performance of state-of-the-art algorithms for
highly specified and engineered domains, while simultaneously we maintain the
flexibility offered by aProbLog in handling complex relational domains. Our
motivation is that faithfully capturing the distribution of probabilities is
necessary to compute an expected utility for effective decision making under
uncertainty: unfortunately, these probability distributions can be highly
uncertain due to sparse data. To understand and accurately manipulate such
probability distributions we need a well-defined theoretical framework that is
provided by the Beta distribution, which specifies a distribution of
probabilities representing all the possible values of a probability when the
exact value is unknown.Comment: Accepted for presentation at AAAI 201
- …